Abstract

The dog was the first domesticated animal but it remains uncertain when the domestication process began and whether it occurred just once or multiple times across the Northern Hemisphere. To ascertain the value of modern genetic data to elucidate the origins of dog domestication, we analyzed 49,024 autosomal SNPs in 1,375 dogs (representing 35 breeds) and 19 wolves. After combining our data with previously published data, we contrasted the genetic signatures of 121 breeds with a worldwide archeological assessment of the earliest dog remains. Correlating the earliest archeological dogs with the geographic locations of 14 so-called "ancient" breeds (defined by their genetic differentiation) resulted in a counterintuitive pattern. First, none of the ancient breeds derive from regions where the oldest archeological remains have been found. Second, three of the ancient breeds (Basenjis, Dingoes, and New Guinea Singing Dogs) come from regions outside the natural range of Canis lupus (the dog's wild ancestor) and where dogs were introduced more than 10,000 y after domestication. These results demonstrate that the unifying characteristic among all genetically distinct so-called ancient breeds is a lack of recent admixture with other breeds likely facilitated by geographic and cultural isolation. Furthermore, these genetically distinct ancient breeds only appear so because of their relative isolation, suggesting that studies of modern breeds have yet to shed light on dog origins. We conclude by assessing the limitations of past studies and how next-generation sequencing of modern and ancient individuals may unravel the history of dog domestication.

A neighbor-joining tree depicting the relationships between 35 breeds (with sample sizes) and rooted with New and Old World Wolves. All clades have been collapsed. Gray branches are poorly supported, whereas black branches and black circles indicate bootstrap values >95%. Clade colors depict breeds that retain a basal signature (red), non-European breeds that are not basal (blue), and European breeds that are rumored to have deep histories but are not basal (brown). The well-supported relationships between Rottweilers and Doberman Pinschers, Neapolitan Mastiffs, Mastiffs, English Bulldogs, Boxers, Shetland Sheepdogs, and Pembroke Welsh Corgis are the result of known or suspected recent admixture between these breeds. The well-support relationship between Dachshunds and English Setters reflects a recent interbreeding between the Dachshund individuals used in this study with English Setters.

A world map in which the approximate maximal range of gray wolves (Canis lupus) is shaded in gray (based on ref. ). Green circles represent regions where confidently dated remains of domestic dogs have been described in at least one archeological site (Table S3). Circles are divided into eight segments, each of which represents 1,500 y, visually depicting the age of the oldest remains at sites in the region over which the circle sits. Filled circles represent remains older than 10,500 y. Each red dog represents a basal breed. The number under each dog refers to the breeds in ; their locations are based upon their suspected geographic origins, described in Table S1.